LU505366B1

LU505366B1 - Method and system for equalizing electric quantity of battery set, and battery management system

Info

Publication number: LU505366B1
Application number: LU505366A
Authority: LU
Inventors: Hongwei Peng
Original assignee: Eve Power Co Ltd
Priority date: 2022-10-26
Filing date: 2023-10-25
Publication date: 2024-04-26
Also published as: WO2024087386A1; CN115498737A

Abstract

An method and system for equalizing electric quantity of a battery set, and a battery management system are provided. The method includes acquiring a cell state of each of unit cells in a battery set; determining a cell operating condition of a corresponding one of the unit cells based on the cell state of each of the unit cells; determining whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and carrying out electric quantity equalization on the at least one target cell.

Description

METHOD AND SYSTEM FOR EQUALIZING ELECTRIC QUANTITY OF LU505366

BATTERY SET, AND BATTERY MANAGEMENT SYSTEM

TECHNICAL FIELD

[0001] The present application relate to the technical field of power batteries, and for example, to a method and a system for equalizing electric quantity of a battery set, and a battery management system.

BACKGROUND

[0002] Currently, a battery set of an electric automobile is mostly formed by connecting unit cells in series. Since unit cells have differences in the manufacturing process and in the cyclic charging and discharging process of the battery set, the unit cells are not completely consistent in terms of rated capacity, voltage, internal resistance, and the like. The inconsistency of the battery set is an important factor causing the performance degradation of the entire battery set. The un-equalized characteristic of the battery set reduces the capacity and the energy utilization rate of the battery set, reduces the input/output power level of the battery set, and shortens the service life of the battery set. In order to improve the consistency of a battery pack in use, it is necessary to equalize the battery pack according to the un-equalization between the electrode cores.

[0003] In the related art, a battery is usually screened before being assembled into a battery pack. At the initial stage of use of a battery set, the uniformity of unit cells is good, but inconsistencies still exist as the service time of the battery set increases. Equalization adjustment is generally used in an application process of the battery set. However, in a related art, equalization is generally performed under a constant operating condition in an equalization process, and equalization control is insufficient, thereby affecting the consistency and the equalization effect of the battery set.

SUMMARY

[0004] According to some embodiments of the present application, it is provided a method and a system for equalizing electric quantity of a battery set, and a battery management system, which increases equalization flexibility, improves consistency of the battery set, and improves available capacity and available energy of 1 the battery set. LU505366

[0005] According to a first aspect, it is provided an electric quantity equalization method for a battery set including: acquiring a cell state of each of unit cells in a battery set; determining a cell operating condition of a corresponding one of the unit cells based on the cell state of each of the unit cells; determining whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and carrying out electric quantity equalization on the at least one target cell.

[0006] According to a second aspect, it is provided A battery equalization control system for a battery set including: an acquiring module configured to acquire a cell state of each of unit cells in a battery set; a condition determining module configured to determine a cell operating condition of a corresponding one of the unit cells according to the cell state of each of the unit cells; a determining module configured to determine whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and an equalizing module configured to equalize electric quantity of the at least one target cell.

[0007] According to a third aspect, it is provided a battery management system including a battery equalization control system for a battery set, the battery equalization control system including: an acquiring module configured to acquire a cell state of each of unit cells in a battery set; a condition determining module configured to determine a cell operating condition of a corresponding one of the unit cells according to the cell state of each of the unit cells; a determining module configured to determine whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and an equalizing module configured to equalize electric quantity of the at least one target cell, in which the battery management system includes a second battery management unit, a voltage acquisition management unit, and a battery temperature unit, the condition 2 determining module and the determining module are integrated in the second battery LU505366 management unit, the acquiring module is integrated in the voltage acquisition management unit and the battery temperature unit, and the equalizing module is integrated in the voltage acquisition management unit.

[0008] According to the technical solution provided in the embodiment of the present application, a present cell operating condition of a battery set is determined by a cell state of each unit cell, and the battery set is performed the equalization determination according to different cell operating conditions. If the equalizing requirement is met, target cell(s) to be equalized in the battery set are determined according to the cell states and the cell operating conditions, so that the electric quantities of the target cell(s) are equalized. The target cell(s) are determined and selected based on cell operating conditions, thereby avoiding the limitation of equalization determination under a single operating condition. In this way, the flexibility of electric quantity equalization is improved, the consistency of the battery set is enhanced, and the usable capacity and the usable energy of the battery set 1s further enhanced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a schematic flow diagram of an electric quantity equalization method of a battery set according to embodiments of the present application;

[0010] FIG. 2 is a schematic flow diagram of battery equalization determination of a battery set in an end-of-charging condition according to embodiments of the present application;

[0011] FIG. 3 is a flowchart for determining a target cell to be equalized in a battery set based on a cell state and a cell operating condition according to embodiments of the present application;

[0012] FIG. 4 is a schematic diagram of a process for selecting a target cell in battery equalization determination of a battery set under a sufficient standing operating condition according to embodiments of the present application;

[0013] FIG. 5 is another schematic diagram of a process for selecting a target cell in battery equalization determination of a battery set under a sufficient standing 3 operating condition according to embodiments of the present application; LU505366

[0014] FIG. 6 is a schematic flow diagram of battery equalization determination of a battery set under a charge-up operating condition according to embodiments of the present application;

[0015] FIG. 7 is a schematic structural diagram of a battery equalization control system of a battery set according to embodiments of the present application;

[0016] FIG. 8 is a schematic structural diagram of a battery management system according to embodiments of the present application;

[0017] FIG. 9 is a flowchart of an equalization control method according to embodiments of the present application;

[0018] FIG. 10 is a schematic flow diagram of an equalization determination according to embodiments of the present application;

[0019] FIG. 11 is a schematic diagram for processing an equalization determination according to embodiments of the present application;

[0020] FIG. 12 is a schematic diagram of a circuit structure of an equalizing module according to embodiments of the present application; and

[0021] FIG. 13 is a schematic structural diagram of an equalization branch according to embodiments of the present application.

DETAILED DESCRIPTION

[0022] FIG. 1 is a schematic flow diagram of an electric quantity equalization method for a battery set according to embodiments of the present application. The present embodiment is applicable to a battery equalization case. The method may be performed by a battery equalization control system. The apparatus may be implemented in a manner of hardware and/or software. The method includes steps

S110 to S140.

[0023] At step S110, a cell state of each unit cell in a battery set is acquired.

[0024] The cell state refers to an operating state of a unit cell, and the operating state is characterized by parameters such as a current, a voltage, and a temperature of the unit cell. The operation state of the unit cell can be acquired through corresponding acquisition equipment such as a sensor and a sensor chip. 4

[0025] At step S120, a cell operating condition of the unit cell according to the LU505366 cell state thereof is determined.

[0026] Illustratively, the battery set has charging and standing processes in use, so the operating conditions of the battery set include at least one of an end-of-charging operating condition, a sufficient standing operating condition, and a charge-up operating condition. Illustratively, the end-of-charging operating condition refers to a state in which the charging current drops to an end and the battery is fully charged. The sufficient standing operating condition means that the current of the battery lasts for a preset time period when this current is less than the preset current, which can be considered that the battery is sufficient standing. Or, in a read-system time from power-down at a low voltage to power-up again of the battery management system, if the power-up time and the last power-down time exceed the preset time, it is also considered that the battery is sufficient standing.

[0027] The charge-up operating condition includes a charging operating condition and a post-charging operating condition. The charging operating condition means that the unit cell can continuously have a charging current above a preset current for a certain time. For example, the unit cell can continuously have a charging current above 2A for 5 seconds. The post-charging operating condition means that the current in the preset interval persists for more than the preset time from the charge-up operating condition or the end-of-charging operating condition. That is, the current jumps to the post-charging operating condition. For example, if the current between -2A and 10A persists for more than one minute, the current jumps to the post-charging operating condition. If there is a discharge current in excess of 10A, the current jumps to a non-charging state. The preset time and the corresponding voltage setting may be selected according to the battery type.

[0028] At step S130, the battery set is equalized according to the cell operating condition, and in response to determine that the battery set needs to be equalized, target cell(s) to be equalized in the battery set are determined according to the cell states and the cell operating conditions.

[0029] For example, an un-equalization degree of a battery set in a corresponding operating condition is determined according to a determined cell operating condition. If equalization is required, a cell to be equalized is determined 5 and marked based on parameters such as current and voltage of the cell under the LU505366 pesent corresponding operating condition, so as to obtain the target cell(s). For example, an end-of-charging operating condition is used as an example to determine the equalization, and a first threshold voltage and a second threshold voltage are determined according to battery performance. For example, taking a battery that is an iron phosphate battery as an example, the first threshold voltage VL1 is selected to be 3.5V and the second threshold voltage VH is selected to be 3.55V. If the voltages of all the unit cells are less than the first threshold voltage VL1, it indicates that the voltages of all the unit cells are low, and no equalization is required at this time. If the voltages of all the unit cells are greater than the second threshold voltage VH, it indicates that the voltages of all the unit cells reach the voltage target, and the cells do not need to be equalized. If the voltages of some of the unit cells are greater than the second threshold voltage VH and the voltages of other unit cells are less than the first threshold voltage VL 1, the voltages of the unit cells are inconsistent and the unit cells further have an un-equalization defect, which indicates that the unit cells need to be equalized.

[0030] When the average voltage of the unit cells is less than the first threshold voltage VL1 at the end-of-charging operating condition, it indicates that there are more unit cells with low voltages. Therefore, it is necessary to perform discharge equalization for a longer time at the same current for the unit cells with voltages higher than the second threshold voltage VH. If the average voltage is greater than or equal to the first threshold voltage VL1, it indicates that there are fewer unit cells with low voltages. Therefore, it is necessary to perform discharge equalization for a shorter time at the same current for the unit cells with voltages higher than the second threshold voltage VH. In order to improve the determination of the equalization degree, a comparison threshold value may be added adaptively. For example, a third threshold voltage VL2 is added and selected to be 3.45V, a fourth threshold voltage VL3 is added and 3.39V, and a minimum voltage in the unit cell is obtained. The minimum voltage refers to a minimum voltage in voltages of all the unit cells. The minimum voltage is greater than or equal to the third threshold voltage

VL2, and a cell whose voltage is higher than the second threshold voltage VH may be selected as the target cell. If the average voltage (the average voltage refers to an average value of the voltages of all the unit cells) of the unit cells at this time is less 6 than the first threshold voltage VL1, there are more unit cells with the low voltages. LU505366

Therefore, the unit cells each having a voltage higher than the second threshold voltage VH are used as the target cells, and discharge equalization of the first electric quantity is performed. If the average voltage is greater than or equal to the first threshold voltage VL1, there are fewer unit cells with the low voltages. Therefore, discharge equalization of the second electric quantity needs to be performed for the target cells each having a voltage higher than the second threshold voltage VH, so as to avoid over-equalization. The first electric quantity is less than the second electric quantity. If the minimum voltage is less than the third threshold voltage VL2, the cell whose voltage is higher than the first threshold voltage VL1 is discharged as the target cell. To further subdivide the discharge equalization electric quantity, the fourth threshold voltage VL3 can be used to divide the discharge equalization electric quantity accordingly to ensure equalization performance. For example, if the minimum voltage is less than the third threshold voltage VL2 and not less than the fourth threshold voltage VL3, the cell whose voltage is higher than the first threshold voltage VL1 is discharged as the target cell to discharge, and discharge equalization of the third electric quantity is performed. If the minimum voltage is less than the fourth threshold voltage VL3, the cell whose voltage is higher than the first threshold voltage VL1 is discharged as the target cell to discharge, and discharge equalization ofthe fourth electric quantity is performed. The third electric quantity is less than the fourth electric quantity.

[0031] At step S140, electric quantity equalization is carried out on the target cell(s).

[0032] Tllustratively, under the corresponding operating condition, each of the target cells has corresponding equalization time, so that the cell is equalized according to the cell operating condition. Illustratively, in the end-of-charging operation, the minimum voltage is greater than or equal to the third threshold voltage VL2. If the average voltage is less than the first threshold voltage VL1, it indicates that there are more unit cells each having a low voltage. Therefore, it is necessary to select an equalization of the first electric quantity for the unit cells each having a voltage higher than the second threshold voltage VH. For example, the 0.7% of actual cell capacity is equalized. If the average voltage is greater than or equal to the first threshold voltage

VLI, it indicates that there are fewer unit cells each having a low voltage. Therefore, 7 it is necessary to perform discharge equalization of the second electric quantity for the LU505366 target cells each having a voltage higher than the second threshold voltage VH. For example, the 0.5% of the actual cell capacity is equalized, so as to avoid the over-equalization. If the minimum voltage is less than the third threshold voltage VL2 and not less than the fourth threshold voltage VL3, discharge equalization of the third electric quantity is performed for cells each having a voltage higher than the first threshold voltage VL1. For example, 1% of actual cell capacity is equalized. If the minimum voltage is less than the fourth threshold voltage VL3, discharge equalization at the fourth electric quantity is performed for cells each having a voltage higher than the first threshold voltage VL1. For example, 2% of actual cell capacity is equalized, so that the batteries having different voltage equalizations can selects appropriate electric quantity equalization depending on different operating conditions.

[0033] According to the technical solution provided in the embodiment of the present application, a present operating condition of a battery set is determined by a cell state of each unit cell, equalization determination is performed on the battery set according to different cell operating conditions. If the equalizing requirement is met, the target cell(s) to be equalized in the battery set are determined according to the cell states and the cell operating conditions, so that electric quantities of the target cell(s) are equalized.

[0034] FIG. 2 is a schematic flow diagram of battery equalizing determination of a battery set in an end-of-charging condition according to embodiments of the present application. Referring to FIG. 2, the method includes the following steps 210 to S230

[0035] At step S210, a first threshold voltage and a second threshold voltage are determine based on the unit cells, and the first threshold voltage is less than the second threshold voltage.

[0036] By way of example, when the charging is ended, an equalization determination is made in accordance with the voltage situation of the unit cells, and two threshold voltages are set, namely, a first threshold voltage VL1 and a second threshold voltage VH. Illustratively, taking the battery that is an iron phosphate battery as an example, the first threshold voltage VL1 is 3.5V and the second threshold voltage VH is 3.55V. For different types of batteries, the first threshold 8 voltage VL1 and the second threshold voltage VH that are different need to be LU505366 selected. Illustratively, the first threshold voltage VL1 is selected to be a voltage value corresponding to about 98.5% of state of charge (referred briefly to as SOC) value reached by the unit voltage at the end of charging moment, and the second threshold voltage VH is selected to be a voltage value corresponding to about 99% of the SOC value reached by the unit voltage at the end of charging moment. The size of the SOC value may be adjusted according to the range of the equalization voltage difference required by the cells. For example, if the SOC of the first threshold voltage VL1 differs greatly from the SOC of the second threshold voltage VH, the voltage range composed of the first threshold voltage VL1 and the second threshold voltage VH becomes larger. That is, the range of the equalization required by the cells becomes less, which is equivalent to reducing the equalization requirements. If the SOC of the first threshold voltage VL1 differs slightly from the SOC of the second threshold voltage VH, the voltage range composed of the first threshold voltage VL1 and the second threshold voltage VH becomes less. That is, the range of the equalization required by the cells becomes larger, which is equivalent to improving the equalization requirements.

[0037] At step S220, a voltage of each unit cell in the battery set is acquired.

[0038] At step S230, equalization determination is performed on the battery set according to a relationship among voltages of unit cells, a first threshold voltage, and a second threshold voltage. If the voltages of at least some unit cells are less than the first threshold voltage, and the voltages of at least other unit cells are greater than the second threshold voltage, it is determined that the battery set needs to be equalized.

[0039] Tllustratively, if the voltages of all the unit cells are less than the first threshold voltage VLI, it is indicated that the voltages thereof do not meet the requirements, and that the unit cells do not need to be equalized. If all voltages are greater than the second threshold voltage VH, it indicates that the voltages and the

SOC of the unit cells substantially meet the charging requirements, and each unit cell does not need to be equalized. If some of the voltages of the unit cells are greater than the second threshold voltage VH and some voltages are less than the first threshold voltage VL1, that is, if the voltages of the unit cells are partially high and partially low, it indicates that there is a consistency defect between the cells, and it is 9 determined that the battery set at this time needs to be equalized. LU505366

[0040] Based on the above embodiment, FIG. 3 is a schematic flowchart for determining a target cell to be equalized in a battery set based on a cell state and a cell operating condition according to embodiments of the present application. Referring to

FIG. 3, the method includes the following steps 310 to 320.

[0041] At step S310, a third threshold voltage is determined based on the unit cells, and the third threshold voltage is less than the first threshold voltage.

[0042] Tllustratively, for different types of batteries, it is continued to be necessary to select a different third threshold voltage VL2, which is less than the first threshold voltage VL1. Illustratively, taking the battery that is an iron phosphate battery as an example, the third threshold voltage VL2 is 3.45V. Illustratively, the third threshold voltage VL2 is selected to be a voltage value corresponding to about 97% of the SOC value reached by the unit voltage at the end of charging moment.

Herein, the size of the SOC value may be adjusted according to the range of the equalization voltage difference required by the cells. A SOC value corresponding to the third threshold voltage VL2 is set to be less than a SOC value corresponding to the first threshold voltage VL1. A plurality of groups of threshold voltages may be set to perform threshold division, so that the equalization determination and the selection criteria of the battery are improved by the threshold division, the target cell screening is better, and thus the equalization effect is further improved. For example, for different types of batteries, the fourth threshold voltage VL3, which is less than the third threshold voltage VL2, is continuously selected. For example, taking the battery that is an iron phosphate battery as an example, the fourth threshold voltage VL3 is 3.39V. Illustratively, the selection criterion of the fourth threshold voltage VL3 is that the unit voltage at the end of charging moment reaches a voltage value corresponding to about 96% of the SOC value.

[0043] At step S320, target cell(s) are determined based on a minimum voltage, a first threshold voltage, a second threshold voltage, and a third threshold voltage of the unit cell. If the minimum voltage among the unit cells is greater than or equal to the third threshold voltage, the unit cell whose voltage is greater than the second threshold voltage is marked the target cell.

[0044] If the minimum voltage of the unit cell is less than the third threshold 10 voltage, the unit cell whose voltage is greater than the first threshold voltage is LU505366 marked the target cell.

[0045] Tllustratively, the minimum voltage in voltages of the unit cells is obtained, the minimum voltage is greater than or equal to the third threshold voltage

VL2, and thus a cell having a voltage higher than the second threshold voltage VH can be selected as the target cell for discharge equalization. If the average voltage of each unit cells is less than the first threshold voltage VL1 at this time, the unit cells having the low voltages are more, unit cells each having a voltage larger than the second threshold voltage VH are served as target cells and thus discharge equalization is performed for a longer time at the same current. If the average voltage is greater than or equal to the first threshold voltage VL1, the unit cells each having the low voltage is fewer, thus it is necessary to perform discharge equalization for a shorter time at the same current for the target cells each having the voltage is higher than the second threshold voltage VH. If the minimum voltage is less than the third threshold voltage VL2, the cell whose voltage is higher than the first threshold voltage VLI1 is discharged as the target cell. In order to subdivide the discharge equalization electric quantity, the fourth threshold voltage VL3 may be used to divide the discharge equalization electric quantity correspondingly to ensure equalization performance. For example, if the minimum voltage is less than the third threshold voltage VL2 and not less than the fourth threshold voltage VL3, the cell whose voltage is higher than the first threshold voltage VL1 is discharged as the target cell, and discharge equalization of the third electric quantity is performed. If the minimum voltage is less than the fourth threshold voltage VL3, the cell whose voltage is higher than the first threshold voltage VL1 is discharged as the target cell, and discharge equalization of the fourth electric quantity is performed. The third electric quantity is less than the fourth electric quantity.

[0046] Tllustratively, the first threshold voltage is a voltage value at a first preset state of charge reached by the unit voltages of the unit cells at a first end-of-charging moment. The second threshold voltage is a voltage value at a second preset state of charge reached by the unit voltages of the unit cells at a second end-of-charging moment. The third threshold voltage is a voltage value at a third preset state of charge reached by the unit voltages of the unit cells at a third end-of-charging moment. The voltage value at the second preset state of charge is 11 greater than the voltage value at the first preset state of charge. The voltage value at LU505366 the first preset state of charge is greater than voltage value at the third preset state of charge.

[0047] Tllustratively, for different types of batteries, the first threshold voltage

VLI, the second threshold voltage VH, and the third threshold voltage VL2 that are different need to be selected. In order to increase the accuracy of the equalization determination, the fourth threshold voltage VL3 may continue to be selected, the corresponding voltage values in different state of charges may be selected, and the battery equalization determination screening criteria may be improved by setting a plurality of groups of threshold voltages. For example, taking the battery that is an iron phosphate battery as an example, the first threshold voltage VL1 is 3.5V, the second threshold voltage VH is 3.55V, the third threshold voltage VL2 is 3.45V, and the fourth threshold voltage VL3 is 3.39V. The first threshold voltage VL1 is a voltage value corresponding to about 98.5% of a SOC value reached by the unit voltage at the end of charging moment, the second threshold voltage VH is a voltage value corresponding to about 99% of the SOC value reached by the unit voltage at the end of charging moment, and the third threshold voltage VL2 is a voltage value corresponding to about 97% of the SOC value reached by the unit voltage at the end of charging moment, and the fourth threshold voltage VL3 is a voltage value corresponding to about 96% of the SOC value reached by the unit voltage at the end of charging moment. The size of the SOC value may be adjusted according to the range of the equalization voltage difference required by the cells. For example, if the

SOC of the first threshold voltage VL1 differs greatly from the SOC of the second threshold voltage VH, the voltage range composed of the first threshold voltage VL1 and the second threshold voltage VH becomes larger. That is, the range of the equalization required by the cells becomes less, which is equivalent to reducing the equalization requirements. If the SOC of the first threshold voltage VL1 differs slightly from the SOC of the second threshold voltage VH, the voltage range composed of the first threshold voltage VL1 and the second threshold voltage VH becomes less. That is, the range of the equalization required by the battery becomes larger, which is equivalent to improving the equalization requirements. The SOC values corresponding to the third threshold voltage VL2 and the fourth threshold voltage VL3 are each set to a SOC value that is less than the first threshold voltage 12

VL1, so that the equalizing determination and the screening criteria of the battery are LU505366 improved by threshold division, the target cell screening is better, and the equalization effect is further improved.

[0048] FIG. 4 is a schematic diagram of a process for selecting a target cell in battery equalizing determination of a battery set under a sufficient standing operating condition according to embodiments of the present application. Referring to FIG. 4, the method includes the following steps S410 to S430.

[0049] At step S410, battery capacities of the unit cells and an average capacity of the unit cells are acquired in response to an open circuit voltage of each of the unit cells after sufficient standing being within a linear variation interval of a relation curve between the open circuit voltage and a state of charge of the unit cell.

[0050] Tllustratively, after the cell is sufficient standing, the voltage of the cell is an open circuit voltage (referred briefly to as OCV). That the cell is sufficient standing refers to a battery managing system (referred briefly to as BMS) of the battery energy storage system is not powered down, and the cell is considered to be sufficient standing when the current is less than a predetermined current and lasts for a predetermined time. For example, the current is less than 0.1C and lasts for one hour, which is considered that the cell is sufficient standing. Alternatively, in a case where the BMS is powered down at a low voltage, in the read-system time after power-up again and if the power-up time and the last power-down time exceed the preset time, the cell can also be considered to be sufficient standing.

[0051] The OCV-SOC relation curve may determine the corresponding value of the open circuit voltage at different SOC values. Here, depending on the type of the battery, the OCV-SOC relation curve includes a corresponding linear variation interval. For example, taking the battery that is an iron phosphate battery as an example, the open circuit voltage range of the OCV-SOC linear interval is 2.5V-3.27V, and other voltages are considered to be in a non-linear interval.

[0052] At step S420, a reference capacity threshold is determined based on the battery capacities and the average capacity.

[0053] Illustratively, the reference capacity threshold is a determination threshold in which the unit cell needs to be equalized. In the OCV-SOC linear variation interval, the SOC value of the unit cell is estimated by using the OCV of the 13 unit cell, the present battery capacity of each unit cell is calculated from the SOC LU505366 value, and the equalizing control is performed on the battery according to the difference between the battery capacities. The average capacity of the cells is calculated, and a value of summing the average capacity and a value of the battery capacity multiplying by the weight (e.g., the weight is taken as 50%) is used as the reference capacity threshold. Considering the average capacity and the battery capacity, a single parameter selection is avoided, and data accuracy is improved.

Here, the weight is the proportion of the average capacity to the battery capacity, and this weight is adjustable according to the actual situation and has greater flexibility.

[0054] At step S430, each of the at least one target cell is determined according to a corresponding one of the battery capacities and the reference capacity threshold, in which in response to the corresponding one of the battery capacities being greater than the reference capacity threshold, one of the unit cells which has the corresponding one of the battery capacities is marked as the target cell.

[0055] Tllustratively, a cell whose capacity is higher than the reference capacity threshold is discharge-equalized. Illustratively, in order to ensure that the cell capacity is not over-equalized, the reference capacity threshold plus a preset multiple of the present actual capacity of the unit cell may be determined as the floating amount. For example, a unit cell whose capacity is higher than the reference capacity threshold plus 1.5% multiplied by the present actual capacity may be determined as the target cell. The preset multiple may be selectively adjusted according to the actual application. In subsequent equalization, the discharge capacity of the cell to be equalized is equal to the present battery capacity of the unit cell minus a reference capacity threshold.

[0056] FIG. 5 is another schematic diagram of a process for selecting a target cell in battery equalizing determination of a battery set under a sufficient standing operating condition according to embodiments of the present application. Referring to

FIG. 5, the method includes the following steps S510 to S530.

[0057] At step S510, the unit voltages of the unit cells, an average voltage of the unit cells, and the minimum one of the unit voltages of the unit cells are acquired in response to the open circuit voltage being within a non-linear variation interval of the relation curve between the open circuit voltage and the state of charge. 14

[0058] Tllustratively, since the SOC value of each unit cell cannot be obtained LU505366 from OCV when the open circuit voltage is in the OCV-SOC nonlinear variation interval. So, the voltage difference method is used to determine the cell to be equalized and the equalization time, the voltage of each unit cell and the minimum voltage among the voltages are obtained by the collecting device, and the average voltage of the unit cells is obtained from the voltages of the unit cells.

[0059] At step S520, a first reference voltage is determined based on the average voltage of the unit cells and the minimum one of the unit voltages of the unit cells.

[0060] Tllustratively, the first reference voltage is a determination threshold at which the unit cell needs to be equalized, and the average voltage and the minimum voltage are summed and averaged to serve as the first reference voltage.

[0061] At step S530, the target cell is determined according to the unit voltage of the unit cell and the first reference voltage, in which in response to a difference between the unit voltage of the unit cell and the first reference voltage being greater than an equalization preset value, the unit cell which has the unit voltage is marked as the target cell.

[0062] Illustratively, if the difference between the voltage of the unit cell and the first reference voltage is greater than or equal to the preset difference, the unit cell is determined to be the target cell to be equalized. Since the equalization electric quantity or the equalization time of the cell is correspondingly set by setting different preset differences, the corresponding equalization time can be performed by grading according to the preset differences, thereby improving the equalization degree. For example, if the difference value between the voltage of the unit cell and the first reference voltage is greater than or equal to 30mv, it is determined that the cell needs to be equalized for 20 hours at the same current. If the difference value between the voltage of the unit cell and the first reference voltage is greater than or equal to 15mv, it is determined that the cell needs to be equalized at the same current for 10 hours.

[0063] FIG. 6 is a schematic flow diagram of battery equalization determination of a battery set under a charge-up operating condition according to embodiments of the present application. Referring to FIG. 6, the method includes the following steps S610 to S620. 15

[0064] At step S610, the unit voltages of the unit cells, an average voltage of LU505366 the unit cells, the minimum one of the unit voltages of the unit cells, and a maximum one of the unit voltages of the unit cells in a charging process are acquired.

[0065] The maximum voltage Vr of the unit cell during the charging process refers to a voltage corresponding to the moment at which the apparent turning point occurs during the voltage rise of the unit cell in the charging process. For example, taking a lithium iron phosphate battery as an example, the lithium iron phosphate battery has a maximum voltage Vr of 3.4V.

[0066] At step S620, if any one of the unit voltages of the unit cells is greater than the maximum unit voltage, it is determined that the battery set needs to be equalized; and a second reference voltage is acquired according to the average voltage of the unit cells, the minimum unit voltage, and a preset voltage floating amount, and when any one of the unit voltages of the unit cells is greater than the second reference voltage, the unit cell which has the unit voltage is marked as the target cell.

[0067] Tllustratively, the uniformity of the cell voltages can be gradually improved after equalization is performed under the end-of-charging operation.

Furthermore, since the equalization time is a constant and conservative value, it is possible that the equalization time is insufficient for some cells, so that the uniformity of the cell voltages cannot be improved. In order to improve the equalization effect, when the voltage difference between the cells in the charge-up operating condition is relatively large, the equalization determination method based on the voltage difference is used. When the voltage of the unit cell is greater than the maximum voltage Vr, the equalized target cell needs to be re-determined. The second reference voltage is a determination threshold value for screening the target cell, and the average voltage and the minimum voltage are summed, and then averaged and added with a predetermined voltage preset floating amount, so as to serve as the second reference voltage. The voltage preset floating amount can be configured according to battery performance. For example, if the maximum voltage Vr of the lithium iron phosphate battery is 3.4V during charging, and the second reference voltage is equal to 20mV plus an average value of the average voltage and the minimum voltage, the cell whose voltage is greater than the second reference voltage is determined as the target cell, and the equalization time is 3 minutes. Since the voltage in the charge-up 16 operating condition changes rapidly, the target cell is determined again every 3 LU505366 minutes according to the voltage difference between the unit cells.

[0068] Based on the above embodiment, illustratively, a cell operating condition includes an end-of-charging operating condition, a sufficient standing operating condition, and a charge-up operating condition. The sufficient standing operating condition includes an operating condition in which an open circuit voltage is in a linear variation interval of a relation curve between an open circuit voltage and a state of charge, and an operating condition in which an open circuit voltage is in a non-linear variation interval of a relation curve between an open circuit voltage and a state of charge.

[0069] A priority level of performing electric quantity equalization on the target cell is set to be: a priority of the end-of-charging operating condition is higher than a priority of the open circuit voltage in the linear variation interval; the priority of the open circuit voltage in the linear variation interval is higher than a priority of the open circuit voltage being in the non-linear variation interval; and the priority of the open circuit voltage in the non-linear variation interval the is higher than a priority of the charge-up operating condition.

[0070] Tllustratively, the battery set has charging and standing processes in use, so the operating conditions of the battery set include at least one of an end-of-charging condition, a sufficient standing operating condition, and a charge-up operating condition. Therefore, by setting the equalization priority, when the equalization of the high priority is performed in various operating conditions, the equalization process of the low priority can be triggered only after the equalization processing of the high priority is completed, thereby improving the flexibility of the battery equalization and the equalization effect. Illustratively, in the control process, the initial value of the equalization mode is 0. The equalization mode 1 indicates equalization when the open circuit voltage is in the non-linear variation interval of the relation curve between the open circuit voltage and the state of charge, the equalization mode 2 indicates equalization when the open circuit voltage is in the non-linear variation interval of the relation curve between the open circuit voltage and the state of charge, and the equalization mode 3 indicates equalization at the end-of-charging operating condition. The equalization modes of the charge-up operating operation is stored in memory. The larger the value of the equalization 17 mode is, the higher the priority is. The equalization mode of the low priority can be LU505366 triggered only when the equalized time of the equalization mode of the high priority becomes 0.

[0071] Tllustratively, an electric quantity equalization process for a target cell includes: an equalization temperature of the at last one target cell is acquired, and in response to the equalization temperature being greater than a preset temperature upper limit, the equalization current is decreased, and in response to the equalization temperature being less than a preset temperature lower limit, the equalization current is restored.

[0072] Tllustratively, the preset temperature upper limit and the preset temperature lower limit are set to collect the temperature of the unit cells in the equalization process, that is, the equalization temperature. When the highest equalization temperature is greater than or equal to the preset temperature upper limit, for example, 80°C, the equalization temperature is reduced by reducing the equivalent equalization current. For example, the equalization start command and the equalization stop command are alternately executed, so that the equalization effective current is reduced by one half to reduce the equalization temperature. When the maximum equalization temperature is less than the preset temperature lower limit, the equalization current is restored, the equalization start command is kept, and the equalization process is always executed.

[0073] FIG. 7 is a schematic structural diagram of a battery equalization control system of a battery set according to embodiments of the present application.

Referring to FIG. 7, the battery equalization control system includes: an acquiring module 110 configured to acquire a cell state of a unit cell in a battery set; a condition determining module 120 configured to determine a cell operating condition of a unit cell according to a cell state; a determining module 130 configured to determine whether the battery set needs to be equalized according to the cell operating condition, and if it is determined that the battery set needs to be equalized, to determine a target cell to be equalized in the battery set according to the cell state and the cell operating condition; and an equalizing module 140 configured to equalize the electric quantity of the target cell(s).

[0074] For example, the acquiring module 110 acquires a cell state of a unit 18 cell in a battery set. The condition determining module 120 determines present cell LU505366 operating conditions of the battery set by using the cell states of the unit cells. The determining module performs equalizing determination on the battery set according to different cell operating conditions. If the equalizing requirement is met, the target cell(s) to be equalized in the battery set are determined according to the cell states and the cell operating conditions. The equalizing module 140 performs electric quantity equalization on the target cell(s). The equalizing module 140 determines and selects the target cell(s) according to the cell operating condition, thereby avoiding the condition limitation caused by the equalizing determination in a single operating condition, improving the flexibility of electric quantity equalization, improving the consistency of the battery set, and improving the available capacity and the available energy of the battery set.

[0075] FIG. 8 is a schematic structural diagram of a battery management system according to embodiments of the present application. Referring to FIG. 8, the battery management system includes a battery cluster 810 formed by unit cells connecting in series, a Management Battery Management Unit (MBMU), a Second

Battery Management Unit (SBMU), a voltage acquisition management unit, a battery temperature unit, a High-Voltage Management Unit (HMU), and a Human interface (HMI). It should be noted that the number of the battery clusters 810 can be extended according to the energy storage requirements, so that the management of the high-voltage battery system can be realized.

[0076] Components, which participate in the equalization control, of the battery management system includes the SBMU and the voltage acquisition management unit integrated with the equalizing module. The corresponding functions of both the condition determining module and the determining module are integrated in the SBMU. The equalization strategy is mainly performed by the SBMU to determine the equalization, start and stop the equalization. The SBMU sends a corresponding start or stop equalization command to the voltage acquisition management unit, and the voltage acquisition management unit controls opening and closing of the equalization hardware according to the control command of the SBMU to execute the equalization process of the unit cells. The equalization command is realized by Controller Area Network (referred briefly to as CAN) communication.

The equalization command is sent periodically. The SBMU periodically sends the 19 equalization command to the voltage acquisition management unit. After the voltage LU505366 acquisition management unit receives the equalization command, the voltage acquisition management unit starts or closes the equalization hardware, and sends the equalization execution state through a CAN bus. The voltage acquisition management unit and the battery temperature unit collect parameters such as a voltage, a temperature, and a current of the unit cell. Functions of an acquiring module and an equalizing module may be integrated in the voltage acquisition management unit.

[0077] The battery management system has a variety of external interfaces, which can meet various application requirements. These interfaces include a voltage acquisition input interface, a temperature acquisition input interface, a fan control output interface, a fan signal feedback input interface, a heating control output interface, a CAN2.0 interface, an Ethernet interface, an RS485 interface, a dry contact output interface, a switching value input/output interface, a current high-speed acquisition input interface, and a high-voltage signal acquisition input interface.

[0078] FIG. 9 is another schematic flow diagram of an equalization control method according to embodiments the present application. Referring to FIG. 9, at step

S710, a control entry call is performed each time as a preset time interval elapses.

Exemplarily, the control entry call is started once every 200ms. At step S720, fault information related to the equalization control is obtained. For example, information such as a unit voltage detection fault, a temperature detection fault, a current detection fault, a Voltage Controller Area Network (referred briefly to as V-CAN) communication fault, and a storage fault. At step S730, it is determined that whether the sufficiently standing operating condition is satisfied. If the sufficiently standing operating condition is satisfied, the method goes to step S740, i.e., the determination for equalization based on the sufficiently standing operating condition is marked. If the sufficiently standing operating condition is not satisfied, the method skips step

S740.

[0079] At step S750, it is determined whether the post-charging operating condition is satisfied. If the post-charging operating condition is satisfied, the method goes to step S760, i.e., the determination for equalization based on the post-charging operating condition is marked. If the post-charging operating condition is not satisfied, the method skips step S760. 20

[0080] At step S770, it is determined whether an end-of-charging condition is LU505366 satisfied. If the end-of-charging condition is satisfied, the method goes to step S780, i.e, the determination for equalization based on the end-of-charging condition is marked. If not, the method skips step S780.

[0081] At step S790, it is determined whether or not the condition for calculating equalization is satisfied. The condition for determining the equalization under the sufficient standing operating condition is that the battery management system has no faults related to the inhibition of equalization, such as a unit voltage detection fault, the temperature detection fault, the current detection fault, the V-CAN communication fault, and an Electronic Equipment (referred briefly to as EE) fault, a battery temperature is greater than or equal to 45°C, and an equalization temperature is greater than or equal to 100°C. The difference between the total voltage of voltages of the unit cells received by SBMU and the total voltage detected is less than 10V.

The minimum unit voltage is greater than the voltage threshold lower limit (e.g, 3.1V) that allows the equalization determination under the sufficiently standing operating condition. There is no equalization model with high priority. If the SBMU determines that the above condition is satisfied, a determination for equalization under a sufficiently standing operating condition is triggered once. That is, the method goes to step S800, 1.e., the determination function is invoked to select the target cell(s), and the method also goes to the step S810, i.e., equalization is performed. The SBMU determines the battery to be equalized and the corresponding equalization time according to the unit voltages of the cells, the minimum voltage, the average voltage, the OCV-SOC table, and the like. And, the equalization time is saved in the memory for calling.

[0082] The condition for determining equalization under the post-charging operating condition is that the battery management system has no faults related to the inhibition of equalization, such as the unit voltage detection fault, the temperature detection fault, the current detection fault, the V-CAN communication fault, the storage fault, the battery temperature is greater than or equal to 45°C, and the equalization temperature is greater than or equal to 100°C. The minimum unit voltage is greater than the voltage threshold (e.g, 3.1V) that allows the equalization determination. The current is less than 0.35C, and the maximum voltage of the unit cell remains greater than the maximum voltage Vr (e.g, 3.4V) for more than 1 21 minute. And, it is determined whether the above conditions are met or not every three LU505366 minutes. If the above conditions are met, the equalization determination under the post-charging operating condition is triggered one time. That is, the method goes to the step S800, i.e., the equalization determining function is invoked to select the target cell(s), in which it is determined that an unit cell whose voltage is higher than a value (obtained by averaging a sum of the average voltage and the minimum voltage to obtain an average value and by summing the average value and the voltage preset floating amount (that is configurable, e.g., configured as 20mV)) needs to be equalized, and the method also goes to step S810, i.e., equalization is performed. The equalization time is held for 3 minutes, which is not stored in the memory.

[0083] The condition for determining the equalization under the end-of-charging operating condition is that the battery management system has no faults related to the inhibition of the equalization, such as a unit voltage detection fault, a temperature detection fault, current detection fault, a V-CAN communication fault, a communication fault, a battery temperature is greater than or equal to 45°C, and an equalization temperature is greater than or equal to 100°C. The minimum voltage of the unit cell is greater than the voltage threshold (e.g., 3.1V) that allows the equalization determination. The SBMU determines whether the above condition is satisfied. If the condition is satisfied, an equalization determination is triggered one time under the end-of-charging operating condition. That is, the method goes to step

S800, i.e., a determination function is invoked to select the target cell(s). The SBMU determines the cell(s) to be equalized based on the maximum voltage, the minimum voltage, the average voltage, the second threshold voltage VH, the first threshold voltage VL1, the third threshold voltage VL2, the fourth threshold voltage VL3, and the like. The method goes to step S810, i.e., equalization is performed, according to the equalization time. The equalization time is stored in the memory, and the equalization mode is set to the equalization mode 3.

[0084] If step S790 is not satisfied, the method goes to step S820, i.e. it is determined whether a condition for starting equalization is satisfied. For example, the above condition includes a unit voltage detection fault, a temperature detection fault, a current detection fault, a V-CAN communication fault, a storage fault, a battery temperature is greater than or equal to 45°C, an equalization temperature is greater than or equal to 100°C, and the minimum unit voltage is greater than a voltage 22 threshold (e.g., 3.1V) that allows to start the equalization, which indicates that a LU505366 starting condition is satisfied. The method goes to step S830, i.e, an equalization starting function is invoked to perform a starting operation.

[0085] If the step S820 is not satisfied, the method goes to step S840, i.e, it is determined whether or not the stopping equalization condition is satisfied. The satisfying condition for stopping equalization includes that the battery management system has faults related to inhibiting equalization, such as a unit voltage detection fault, a temperature detection fault, a current detection fault, a V-CAN communication fault, a storage fault, a battery temperature is greater than or equal to 45°C, an equalization temperature is greater than or equal to 100°C, and the like. The minimum voltage is less than or equal to the voltage threshold (e.g, 3.08V) for stopping equalization. When any of the above conditions is satisfied, the SBMU will stop equalization of all cells.

[0086] If the equalization is started by the SBMU, the equalization time needs tobe clocked. As the equalization time for a cell elapses, the equalization mark of the cell needs to be cleared. When the equalization time of all cells is elapsed, the equalization is stopped. When any one of the above cases exists, the method goes to step S850, 1.e., an equalization stopping function is invoked.

[0087] In addition, in order to prevent the equalization time previously determined from being trustworthy due to over-long battery stays, by using step S860, the equalization needs to be cleared is marked in following cases: a time interval between the last power-down time and the present power-on time of the BMS exceeds 240 hours, the BMS has no fault related to the inhibition of equalization; and the

SBMU receives that the difference between the total voltage obtained by summing the cell voltages and the detected total voltage is less than 10V. The method goes to step

S870, i.e, the equalization clearing function is invoked to clear the stored equalization time.

[0088] FIG. 10 is a schematic flowchart for an equalization determination according to embodiments of the present application. Referring to FIG. 10, a determination flow includes an end-of-charging condition, a sufficiently standing operating condition of a battery, and a post-charging condition. The method includes the steps S900 to S1019. 23

[0089] At step S900, the equalization determining function is entered. At step LU505366

S901, equalization is stopped. At step S910, it is determined whether it is the end-of-charging operating condition. If the end-of-charging operating condition is determined, the method goes to step S920, i.e., equalization mark, equalization mode, and equalization time are all cleared. At step S930, it is determined whether the maximum voltage of the unit cell is less than the first threshold voltage VL1, for example, 3.5V. If the maximum voltage is less than the first threshold voltage VLI, it indicates that the voltages of all the unit cells are less than the first threshold voltage

VL1, and further indicates that the voltages do not meet the requirements. In this case, the unit cells do not need to be equalized. If the maximum voltage is greater than the first threshold voltage VL1, the method goes to step S940, ie. it is determined whether the minimum voltage of the unit cell is less than the first threshold voltage

VL1, for example, 3.5V. If the minimum voltage is less than the first threshold voltage VL1, the method goes to step S950, ie, it is determined whether the minimum voltage of the unit cell is less than the third threshold voltage VL2, for example, 3.45V. If the minimum voltage is greater than the third threshold voltage

VL2, the method goes to step S960, i.e, it is determined whether the average voltage is less than the first threshold voltage VL 1. If the average voltage is less than the first threshold voltage VL1 at this time, the method goes to step S970, which indicates that there are more unit cells each having a low voltage and longer equalization time is selected for the unit cells each having a voltage higher than the second threshold voltage VH. For example, the equalization time is equalization time corresponding to the 0.7% of actual cell capacity.

[0090] If the average voltage at this time is greater than the first threshold voltage VL1, the method goes to step S980, which indicates that there are fewer unit cells each having a low voltage. Therefore, it is necessary to perform short-time discharge equalization for the target cell(s) whose voltages are higher than the second threshold voltage VH. For example, the equalization time is set to equalization time corresponding to the 0.5% of actual cell capacity. At step S990, the equalization mark and the equalization time of each cell are updated, and the equalization mode is set to the equalization mode 3. At step S1001, the equalization time and the equalization mode are stored.

[0091] If the minimum voltage is less than the third threshold voltage VL2, 24 the method goes to step S1002, i.e, it is determined whether the minimum voltage of LU505366 the unit cell is less than the fourth threshold voltage VL3, such as 3.39V. If the minimum voltage is greater than the third threshold voltage VL2, the method goes to step S1003, i.e., the equalization time for the cell whose voltage is higher than the first threshold voltage VL1 is set to equalization time corresponding to 1% of the actual cell capacity. If the minimum voltage is less than the third threshold voltage VL2, the method goes to step S1004, i.e., the equalization time for the cell whose voltage is higher than the first threshold voltage VLI is set to equalization time corresponding to 2% of the actual cell capacity.

[0092] If it is determined that it is not the end-of-charging operating condition, the method goes to step S1005, i.e, it is determined whether the cell is sufficiently standing or not, and whether the priority of the present equalization mode is less than the equalization mode 3. If the cell is sufficiently standing, the method goes to step

S1006, i.e., the equalizing mark is cleared, to step S1007, i.e., the reference capacity threshold and the first reference voltage are calculated, and to step S1008, i..e, it is determined whether the open circuit voltage is in a linear interval. If the open circuit voltage is in the linear interval, the method goes to step S1009, i.e, the difference between the battery capacity of each unit cell and the reference capacity threshold is calculated, and the cell whose capacity is higher than the reference capacity threshold is discharged and equalized. For example, to ensure that the cell capacity is not over-equalized, the capacity that obtained by summing the reference capacity threshold and the preset multiple of the present actual capacity of the unit cell may be served as the floating amount to perform the determination. For example, a cell whose capacity is higher than a value of summing the reference capacity threshold and 1.5% of the present actual capacity is determined as the target cell. The preset multiple may be selectively adjusted according to the actual application. In subsequent equalization, the equalized discharge capacity of the cell is equal to the difference between the present cell capacity of the unit cell and the reference capacity threshold. At step

S1010, an equalization mark and equalization time of each unit cell are updated, and the equalization mode is set to the equalization mode 2. At step S1011, the equalization time and the equalization mode are saved.

[0093] If the open circuit voltage is in the non-linear interval, the method goes to step S1012, i.e, it is determined whether the priority of the present equalization 25 mode is lower than the equalization mode 2. If yes, the method goes to step S1013, LU505366 i.e., if the difference between the voltage of each cell and the first reference voltage exceeds the configuration value, and the difference between the voltage of the unit cell and the first reference voltage is greater than or equal to 30mv, the cell is equalized for 20 hours; and If the difference between the voltage of the unit cell and the first reference voltage is greater than or equal to 15mv, the cell is equalized for 10 hours. At step S1014, an equalization mark and equalization time of each cell are updated, and the equalization mode is set to the equalization mode 1. At step S1011, the equalization time and the equalization mode are saved.

[0094] If it is determined that the cell is not under the sufficiently standing operating condition, the method goes to step S1015, 1.e., it is determined whether or not the cell is under the post-charging operating condition. If yes, the method goes to step S1016, 1.e., the equalization mark is cleared, to step S1017, i.e., the second reference voltage is calculated, and to step S1018, 1.e., the unit cell whose voltage minus the second reference voltage exceeds the configuration value is marked as a unit cell to be equalized. At step S1019, the equalization time is set to 3 minutes.

[0095] FIG. 11 is a schematic diagram for processing an equalization determination according to embodiments of the present application. Referring to FIG. 11, at step S1100, the equalization processing is entered. At step S1101, it is determined whether the equalization is in a starting state. If the equalization is in the starting state, the method goes to step S1102, ie. it is determined whether the equalization time based on the voltage difference under the post-charging operating condition is greater than zero. If yes, the method goes to step S1103, ie. the equalization time based on the voltage difference is decreased by 200ms. At step

S1104, it is determined whether the equalization time based on the voltage difference under the post-charging operating condition is zero. If not, the method is returned to step S1102. If yes, the method goes to step S1105, i.e., the equalization mark of each cell is cleared, and the equalization based on the voltage difference is stopped. At step

S1106, it is determined whether to update the equalization mark or the equalization time. If yes, the method goes to step S1107, 1.e., the equalization mark is updated according to the remaining equalization time, and to step S1108, 1.e., it is determined whether the remaining equalization time is not zero. If yes, the method goes to step

S1109, i.e., equalization is started, and to step S1110, it is determined whether the 26 maximum equalization temperature of the cell is greater than or equal to 80°C. If yes, LU505366 the method goes to step S1111, i.e., the equivalent equalization current is decreased. If the maximum equalization temperature of the cell is less than 80°C, the method goes to step S1112, ie, it is determined whether the maximum equalization temperature of the cell is less than 70°C. If yes, the method goes to step S1113, i.e, equivalent current is return to normal. If not, the method goes to step S1114, i.e, it is determined whether the present equalization state is a stop state or the 30-second time period for stopping equalization elapses. If yes, the method goes to step S1115, ie, an equalization instruction for all cells is closed. If not, the method goes to step S1116, 1e, a command for starting or stopping the equalization of the cell is sent according to the equalization mark.

[0096] FIG. 12 is a schematic diagram of a circuit structure of an equalizing module according to embodiments of the present application. FIG. 13 is a schematic structural diagram of an equalization branch according to embodiments of the present application. Referring to FIGS. 12 and 13, a control unit 220 and a plurality of equalization branches 210 are included. Each equalization branch 210 is connected to a unit cell.

[0097] The control unit may include a battery management chip with Model

ADBMS6815, and the resistor R1, the resistor R2, the resistor R4, and the resistor RS are voltage-dividing resistors obtained by the negative temperature coefficient (referred briefly to as NTC) temperature measurement. The resistance value under the present temperature condition is calculated by collecting the voltage-dividing values on the resistor R1, and the temperature value corresponding to the resistance value can be found by searching the Resistor-Temperature (R-T) table of the NTC sensor used for the item.

[0098] The equalization effective current is required to be greater than or equal to 60mA@3.2V, ie, 3.2V is divided by 0.06A, and the corresponding equalization resistance calculated should not exceed 53Q. Since the equalization function is automatically stopped when voltage measurement is used for voltage collection, the maximum effective utilization rate of equalization is generally 90%, and the equalization resistance needs to be controlled below 47.7Q by multiplying 53Q and 90%. In consideration of factors such as certain reservation and resistance accuracy, the actual scheme design of the equalization resistance is 390, and the 27 equalization resistance power is denoted by an equation P=4.2x4.2/39 and the value 0505366 of the equalization resistance power is calculated to be 0.45W, according to the highest equalization voltage denoted by an equation Uc=4.2V. The resistance power is selected to be 1.5W. The resistance drop curve was searched, and it is obtained that the resistance drop rate was 80% at an ambient temperature of 85°C. The corresponding available power is: 1.5Wx0.8=1.2W. Thus, at the ambient temperature of 85°C, the maximum operating power of the equalization resistance is the rated power of the resistance and denoted by an equation 0.45W/1.2W=37.5%. Sufficient power selection is reserved to meet design requirements. Equalization process of equalization branches is as follows.

[0099] The start and the stop of the equalization circuit are controlled by closing and opening of the electronic switch Q1. Illustratively, the electronic switch

Q1 may employ a switch with Model NMOS. At the start of equalization, the control unit outputs a control signal to the control terminal 1 of the electronic switch Q1. The first terminal 2 and the second terminal 3 of the electronic switch Q1 are turned on, and the current of the positive electrode BATO1 01 of the unit cell passes through the resistor R2, the resistor R3, the resistor R4, and the electronic switch Q1 to the negative electrode of the cell, so as to realize the equalization discharge process. At the end of equalization, the control unit outputs a control signal to turn off the electronic switch Q1. For the same other groups of cells, and so on, the equalized discharge control of each unit cell may be realized similarly. 28

Claims

WHAT IS CLAIMED IS: LU505366

1. An electric quantity equalization method for a battery set comprising: acquiring a cell state of each of unit cells in a battery set; determining a cell operating condition of a corresponding one of the unit cells based on the cell state of each of the unit cells; determining whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and carrying out electric quantity equalization on the at least one target cell.

2. The electric quantity equalization method for the battery set according to claim 1, wherein the cell operating condition comprises an end-of-charging operating condition; and determining whether the battery set needs to be equalized according to the cell operating condition comprises: determining a first threshold voltage and a second threshold voltage based on the unit cells; wherein the first threshold voltage is less than the second threshold voltage; acquiring respective unit voltages of the unit cells in the battery set; and determining whether the battery set is equalized based on a relationship among the respective unit voltages of the unit cells, the first threshold voltage, and the second threshold voltage; wherein in response to at least ones of the unit voltages of the unit cells being less than the first threshold voltage and at least other ones of the unit voltages of the unit cells being greater than the second threshold voltage, determining that the battery set needs equalization processing.

3. The electric quantity equalization method for the battery set according to claim 2, wherein determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition comprises: determining a third threshold voltage based on the unit cells, wherein the third threshold voltage is less than the first threshold voltage; determining the at least one target cell based on a minimum one of the unit voltages of the unit cells, the first threshold voltage, the second threshold voltage, and 29 the third threshold voltage; wherein in response to the minimum one of the unit LU505366 voltages of the unit cell being greater than or equal to the third threshold voltage, marking at least one of the unit cells which each has a corresponding one of the unit voltages greater than the second threshold voltage to be the at least one target cell; and in response to the minimum one of the unit voltages of the unit cells being less than the third threshold voltage, marking at least one of the unit cells which each has a corresponding one of the unit voltages greater than the first threshold voltage to be the at least one target cell.

4. The electric quantity equalization method for the battery set according to claim 3, wherein the first threshold voltage is a voltage value at a first preset state of charge reached by the unit voltages of the unit cells at an end-of-charging moment; the second threshold voltage is a voltage value at a second preset state of charge reached by the unit voltages of the unit cells at the end-of-charging moment; the third threshold voltage is a voltage value at a third preset state of charge reached by the unit voltages of the unit cells at the end-of-charging moment; wherein the voltage value at the second preset state of charge is greater than the voltage value at the first preset state of charge; the voltage value at the first preset state of charge is greater than the voltage value at the third preset state of charge.

5. The electric quantity equalization method for the battery set according to claim 4, wherein determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition comprises: determining a fourth threshold voltage based on the unit cells, wherein the fourth threshold voltage is less than the third threshold voltage; determining the at least one target cell based on the minimum one of the unit voltages of the unit cells, the first threshold voltage, the second threshold voltage, the third threshold voltage and the fourth threshold voltage; wherein in response to the minimum one of the unit voltages of the unit cells being greater than or equal to the fourth threshold voltage and less than the third threshold voltage, marking at least one of the unit cells which each has a corresponding one of the unit voltages greater than the first threshold voltage to be the at least one target cell; and in response to the minimum one of the unit voltages of the unit cells being less than the fourth threshold voltage, marking at least one of the unit cells which each has 30 a corresponding one of the unit voltages greater than the first threshold voltage to be LU505366 the at least one target cell.

6. The electric quantity equalization method for the battery set according to any one of claims 1 to 4, wherein the cell operating condition comprise a sufficient standing operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition comprises: acquiring battery capacities of the unit cells and an average capacity of the unit cells in response to an open circuit voltage of each of the unit cells after sufficient standing being within a linear variation interval of a relation curve between the open circuit voltage and a state of charge of the unit cell, determining a reference capacity threshold based on the battery capacities and the average capacity; and determining each of the at least one target cell according to a corresponding one of the battery capacities and the reference capacity threshold, wherein in response to the corresponding one of the battery capacities being greater than the reference capacity threshold, marking one of the unit cells which has the corresponding one of the battery capacities to be the target cell.

7. The electric quantity equalization method for the battery set according to claim 6, further comprising: in response to the corresponding one of the battery capacities being greater than a capacity that is obtained by the reference capacity threshold plus a preset multiple of a present actual capacity of the unit cell, making the unit cell to be the target cell.

8. The electric quantity equalization method for the battery set according to claim 6, wherein determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition further comprises: acquiring the unit voltages of the unit cells, an average voltage of the unit cells, and the minimum one of the unit voltages of the unit cells in response to the open circuit voltage being within a non-linear variation interval of the relation curve between the open circuit voltage and the state of charge; 31 determining a first reference voltage based on the average voltage of the unit cells LU505366 and the minimum one of the unit voltages of the unit cells; and determining each of the at least one target cell according to a corresponding one of the unit voltages of the unit cells and the first reference voltage, wherein in response to a difference between the corresponding one of the unit voltages of the unit cells and the first reference voltage being greater than an equalization preset value, marking one of the unit cells which has the corresponding one of the unit voltages to be the target cell.

9. The electric quantity equalization method for the battery set according to claim 8, wherein in response to a difference between the corresponding one of the unit voltages of the unit cells and the first reference voltage being greater than or equal to a respective one of different preset differences, determining that one of the unit cells which has the corresponding one of the unit voltages is the target cell, and correspondingly setting equalization electric quantity or equalization time of the target cell by setting the different preset differences.

10. The electric quantity equalization method for the battery set according to any one of claims 1 to 4, wherein the cell operating condition comprises a charge-up operating condition; and determining that the at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized comprises: acquiring the unit voltages of the unit cells, an average voltage of the unit cells, the minimum one of the unit voltages of the unit cells, and a maximum one of the unit voltages of the unit cells in a charging process; in response to any one of the unit voltages of the unit cells being greater than the maximum one of the unit voltages, determining that the battery set needs to be equalized; and acquiring a second reference voltage according to the average voltage of the unit cells, the minimum one of the unit voltages of the unit cells, and a preset voltage floating amount, and in response to any one of the unit voltages of the unit cells being greater than the second reference voltage, marking one of the unit cells which has the unit voltage to be the target cell. 32

11. The electric quantity equalization method for the battery set according to LU505366 claim 10, wherein a value of the second reference voltage is a determination threshold value for screening the at least one target cell, and the second reference voltage is obtained by averaging a sum of the average voltage and the minimum one of the unit voltages to obtain an average value and by summing the average value and the voltage preset floating amount.

12. The electric quantity equalization method for the battery set according to any one of claims 1 to 4, wherein the cell operating condition comprises the end-of-charging operating condition, a sufficient standing operating condition, and a charge-up operating condition, wherein the sufficient standing operating condition comprises an operating condition in which an open circuit voltage of each of the unit cells is in a linear variation interval of a relation curve between the open circuit voltage and a state of charge of the unit cell, and an operating condition in which the open circuit voltage is in a non-linear variation interval of the relation curve; setting a priority of equalizing electric quantity of the at least one target cell to be: a priority of the end-of-charging operating condition is higher than a priority of the open circuit voltage in the linear variation interval; the priority of the open circuit voltage in the linear variation interval is higher than a priority of the open circuit voltage in the non-linear variation interval; and the priority of the open circuit voltage in the non-linear variation interval is higher than a priority of the charge-up operating condition.

13. The electric quantity equalization method for the battery set according to any one of claims 1 to 4, wherein carrying out electric quantity equalization on the at least one target cell comprises: acquiring an equalization temperature of the at last one target cell, and in response to the equalization temperature being greater than a preset temperature upper limit, decreasing the equalization current; and in response to the equalization temperature being less than a preset temperature lower limit, restoring the equalization current.

14. A battery equalization control system for a battery set comprising: 33 an acquiring module configured to acquire a cell state of each of unit cells in a LU505366 battery set; a condition determining module configured to determine a cell operating condition of a corresponding one of the unit cells according to the cell state of each of the unit cells; a determining module configured to determine whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and an equalizing module configured to equalize electric quantity of the at least one target cell.

15. A battery management system comprising a battery equalization control system for a battery set, the battery equalization control system comprising: an acquiring module configured to acquire a cell state of each of unit cells in a battery set; a condition determining module configured to determine a cell operating condition of a corresponding one of the unit cells according to the cell state of each of the unit cells; a determining module configured to determine whether the battery set needs to be equalized according to the cell operating condition, and determining that at least one target cell to be equalized in the battery set according to the cell state and the cell operating condition in response to determining that the battery set needs to be equalized; and an equalizing module configured to equalize electric quantity of the at least one target cell; wherein the battery management system comprises a second battery management unit, a voltage acquisition management unit, and a battery temperature unit; wherein the condition determining module and the determining module are integrated in the second battery management unit, the acquiring module is integrated 34 in the voltage acquisition management unit and the battery temperature unit, and the LU505366 equalizing module is integrated in the voltage acquisition management unit.